package oj;

import java.util.Stack;

public class MinStack {
    public Stack<Integer> stack;
    public Stack<Integer> minStack;
    public MinStack() {
        stack = new Stack<>();
        minStack = new Stack<>();
    }

    public void push(int val) {
        stack.push(val);
        if(minStack.empty()){
            minStack.push(val);
        }else{
            int peekVal = minStack.peek();
            if(val <= peekVal){
                minStack.push(val);
            }
        }
    }

    public void pop() {
        if(stack.empty()){
            return;
        }
        int popVal = stack.pop();
        if(popVal == minStack.peek()){
            minStack.pop();
        }
    }

    public int top() {
        if(stack.empty()){
            return -1;
        }
        return stack.peek();
    }

    public int getMin() {
        if (minStack.empty()) {
            return -1;
        }
        return minStack.peek();
    }

    public static void main(String[] args) {
        MinStack s = new MinStack();

        s.push(-2);
        s.push(0);
        s.push(-3);
        s.getMin();
        s.pop();
        s.top();
        s.getMin();
    }
}
